Hauv 20 xyoo tom ntej, peb yuav txuas ntxiv ua lub luag haujlwm ntawm kev ua raws li cov thev naus laus zis tshiab, muab cov khoom lag luam txhim khu kev qha, ua kev tshawb fawb hauv kev tshawb nrhiav ozone daim ntawv thov thiab nce BNP ozone cov khoom lag luam rau ntau daim ntawv thov.